The present invention relates to foods formed of extruded half products of cereal grains such as wheat and corn, and more particularly to half products suitable for expansion or puffing in microwave ovens.
Foods suitable for expanding (i.e. puffing or popping) have been made from extruded flours of cereal grains such as corn, wheat and oats. Other expandable foods include popping corn and amaranth grain. Traditionally, such products have been puffed by deep-fat frying. In recent years, concern about the greasy texture and calorie content of foods prepared by frying in fats or oils, has lead to increasing use of alternatives to deep-fat frying. Among these alternatives is the microwave oven. The widespread household use of microwave ovens has inspired efforts to provide half products and other foods suitable for microwave expansion.
For example, Van Hulle et al U.S. Pat. No. 4,409,250 discloses sugar coated, microwave puffable snacks. Pellets are formed from gelatinized farinaceous doughs, formed from waxy maize, millet, sorghum, milo and rice starches, as well as potato or tapioca starch. Optionally, sucrose and common salt can be added to the dough, to enhance expanding or puffing when the pellets are subject to microwave energy. The pellets are formed by extrusion under pressure and heat, then dried. Before they can be puffed, the pellets much be placed in a puffing medium of water and a carbohydrate sweetening agent.
Wilkinson et al U.S. Pat. No. 4,844,937 discloses a puffable half product made from corn materials, principally corn reduction flour or dry milled horny endosperm flour obtained by tempering whole corn, then running the tempered kernels through a degerminator. The material is combined with moisture, then run through an extruder to gelatinize the starch. A resulting dough is delivered to rotary blender, where the dough pieces are agitated to reduce surface moisture. The pieces then are delivered to a forming extruder where they are shaped, then cut and dried.
Spratt et al U.S. Pat. No. 4,990,348 is directed to half products expanded either by microwave or convection energy. The half products are based on a variety of raw materials including wheat starch, corn meal, potato flour, wheat flour and substantially brand-free oat flour. The material is tempered, heated, then extruded to form an unexpanded starch melt that hardens into a densified, glass-like half product. The product intentionally is cooled rather than dried, causing it to harden without substantially lowering its moisture content, which is said to provide a shelf stable ready to expand half product.
While the above and many other processes have proven satisfactory in connection with certain foods, these approaches do not adequately address the need for a cereal grain half product that undergoes substantial and reliable expansion in consumer microwave ovens.
Therefore, it is an object of the present invention to provide a process for preparing food half products employing moisture levels, temperatures and pressures lower than heretofore considered necessary.
Another object is to provide a half product based predominantly on starch sources other than corn, and at least in part utilizing amaranth flour.
Yet another object of the invention is to provide a food half product expandable in microwave ovens to an expanded volume substantially greater than the unexpanded volume.